This document discusses custom field types in SharePoint. Custom field types allow developers to define custom data structures, validation, and rendering for fields. They combine aspects of fields, web parts, validators, and event receivers. Some examples of when to use custom field types include storing multicolumn data or data related to an external system. The document reviews implementing custom field types including defining the type, properties, validation, and deployment. It also compares custom field types to other extensibility options like content types, web parts, and event receivers.

1. SharePoint Custom Field TypesEugene RosenfeldCTO, Black Blade Associates2-time SharePoint MVPerosenfeld@blackbladeinc.comwww.blackbladeinc.comthingsthatshouldbeeasy.blogspot.com

2. ContentsContentsCustom Field Types Defined

3. Business Cases

4. Custom Field Types and Alternate WSS Extensibility

5. Custom Field Types Implementation

6. DemoCustom Field Types DefinedOverviewCustom field types are Windows SharePoint Service’s mechanism for allowing developers to:

7. Define atomic data structures with custom data structures

8. Custom data validation

9. Custom rendering

10. Custom property storage and processing

11. These items are “what” custom field types can do

12. Custom field types can be thought of as a merging between fields, custom web parts, validators, and event receiversCustom Field Types DefinedCustom Field Type ScenariosCustom field types allow developers to interact with and extend the way in which Windows SharePoint Services organizes, collects, modifies, stores, and displays list item data:

13. Add a field that is based on a custom field type to a list

14. Edit a list field that is based on a custom field type

15. Show data stored in a custom field type instance in the list item display form

16. Show data stored in a custom field type instance in the list item edit form

17. Show data stored in a custom field type instance in the list item new form

18. Show data stored in a custom field type instance in the list view

19. These items describe “when” we would resort to custom field types.Custom Field Types DefinedCustom Data Structures Custom field types may define one or more field data components

20. SharePoint treats all field components as one, indivisible entity

21. SharePoint saves and loads all components of a custom field type as a single unit

22. Any custom data structure is fair game, as long as it is serializable as text

23. Why text, even for booleans, numbers, dates, etc?

24. All data is stored in SQL. Data is retrieved and modified using SQL statements. SQL statements are text, even for logically binary data.Custom Field Types DefinedCustom RenderingDevelopers can associate web controls to display field data to users

25. Think of field render controls as custom web parts that are always associated with all instances of the custom field type

26. Custom rendering controls may include:

27. Web custom controls

28. Client controls or HTML

29. JavaScript

30. AJAX

31. Images

32. Anything else that can render a MIME type that the client browser can interpretCustom Field Types DefinedCustom Field Type PropertiesCustom field types can define custom properties that instances of those field types can set

33. Custom field type properties are meant to allow users to modify the behavior of a custom field type instance

34. These properties can be used to:

35. Set default values for data stored in instance fields

36. Parameterize custom validation logic

37. Control rendering of field data

38. As with the field data, developers can define custom rendering and validation for custom field type properties

39. Custom field properties are very similar to custom web part propertiesBusiness CasesOverviewCustom Data Storage

40. Custom Data Validation

41. Custom Field Rendering

42. Custom Behavioral LogicBusiness CasesCustom Data StorageAtomic multicolumn field

43. Address (street, city, state, zip)

44. Full name (first, middle, last)

45. Geo-data (latitude, longitude, elevation)

46. Pointer to external data

47. Primary key to an external database table

48. Parameter values to a Web Service call

49. URI to external records management systemBusiness CasesCustom Data ValidationData is in a particular format

50. Email

51. SSN

52. Phone number

53. Product code

54. Guid

55. Related data from multiple controls is consistent

56. Address (street, city, state, zip)

57. Full name (first, middle, last)

58. Data is validated against an external entity

59. Database

60. XML file

61. Web Service – address is an actual valid street addressBusiness CasesCustom Field RenderingGraphic

62. Chart

63. Map

64. KPI Indicator

65. Anti-bot / anti-OCR image

66. Embedded object

67. Flash

68. Silverlight

69. ActiveX

70. AJAX

71. Iframe

72. VML / SVG

73. User presence information (name with presence field)Business CasesCustom Behavioral LogicTypically used to control the behavior of the field when it is being populated with data

74. Accessing metadata stored on a system external to SharePoint

75. Custom dialog boxes

76. Wizard interfaces

77. Trees and other navigation elements

78. Asset picker controlCustom Field Types and Alternate WSS ExtensibilityOverviewCustom Field Types and Content Types

79. Custom Field Types and Custom Web Parts

80. Custom Field Types and Event Receivers

81. Custom Field Types and WorkflowsCustom Field Types and Content TypesSimilarities between Custom Field Types and Content TypesBoth can be used to define a grouping or set of discrete data

82. Both can trigger code execution when data changesCustom Field Types and Content TypesDeciding which One to UseUse custom field types when:

83. Must be created by a developer

84. Must be defined using managed code (C#, VB.Net, etc)

85. Can complicate matters when writing code that consumes list field values that are custom field types

86. May prevent the use of third party tools or applications if these can not deal with custom field types

87. Use content types when:

88. Definable by content manager through the web UI

89. Deployable to SharePoint farm as XML (no code needed)Custom Field Types and Custom Web PartsSimilarities between Custom Field Types and Custom Web PartsBoth can define custom rendering for SharePoint data

90. Both can define custom metadata that alters the rendering of the data

91. Both can perform processing logic on their respective data

92. Both can access data outside of SharePoint Custom Field Types and Custom Web PartsDeciding which One to UseUse a custom field type when:

93. You want the custom defined rendering to always be associated with the field data

94. You want to define custom rendering that will be used in the listview web part when the field data is shown in the listview

95. You want to define custom rendering for field data that will be used in all instances of the display item, new item, and edit item forms for list items that contain the a field instance

96. Use a web part when:

97. You want to define custom rendering for a group of fields

98. You want to create views that aggregate information from multiple list items

99. You want to give users the ability to drag the custom rendering onto a web part page through a web browser

100. You want to participate in web part connectionsCustom Field Types and Event ReceiversSimilarities between Custom Field Types and Event ReceiversBoth can be used to run custom code when data in a list is about to change

101. Both can prevent changing list data from being saved to the content database

102. Both can be used to catch field schema changes on listsCustom Field Types and Event ReceiversDeciding which One to UseUse a custom field type when:

103. You want the field code to run for every item an item is changed or added to every list with an instance of the field type exists

104. Note: Two field instances of a custom field type means the code runs twice!

105. Use an event receiver when:

106. You want to be able to activate or deactivate the code for all lists within a particular site (i.e. feature)

107. You need to work with data from several fields in the current list itemCustom Field Types and WorkflowsSimilarities between Custom Field Types and WorkflowsBoth can execute custom code when list item data is changedCustom Field Types and WorkflowsDeciding which One to UseUse a custom field type when:

108. You want the field code to run for every item an item is changed or added to every list with an instance of the field type exists

109. Note: Two field instances of a custom field type means the code runs twice!

110. You want to execute code that finishes running quickly and stores no long-term state information (other than the actual list item field data)

111. Use a workflow when:

112. You want to allow users to be able to associate the code with specific list instances through a web browser

113. You want to give users the option to execute the code automatically or manually

114. Your code needs to run for a long time, over days, weeks, or months

115. You will need to collect information from users involved in the code execution through the browser

116. You need to work with data from several fields in the current list itemCustom Field Types ImplementationOverviewCustom Field Type Definition

117. Custom Field Type Properties

118. Custom Field Data Validation

119. Custom Field Value Classes

120. Custom Field TypeDeploymentCustom Field Types ImplementationCustom Field Type DefinitionA new fldtypes*.xmlfile to hold your field type definition

121. This is the entry point that the WSS runtime uses to start addressing your custom field type

122. Similar in concept to the webtemp*.xml files for site definitions

123. A class the inherits from the SPFieldclass, more commonly, from another class that inherits from SPField, such as SPFieldMultiColumn

124. The type defined by the FieldTypeClassattribute must implement two constructors: public MyFieldComputed (SPFieldCollection fields, string fieldName) : base(fields, fieldName){} public MyFieldComputed (SPFieldCollection fields, string typeName, string displayName) : base(fields, typeName, displayName){} <FieldType> <Field Name="TypeName">MyComputed</Field> <Field Name="TypeDisplayName">$Resources:core,fldtype_computed;</Field> <Field Name="ParentType"> Computed </Field> <Field Name="FieldTypeClass">MySharePoint.MyFieldComputed</Field> <RenderPattern Name="PreviewDisplayPattern"> <HTML><![CDATA[["]]></HTML><Property Select="DisplayName" HTMLEncode="TRUE"/><HTML>"$Resources:core,fldtypes011;</HTML> </RenderPattern> <RenderPattern Name="PreviewEditPattern"><Property Select="DisplayName" HTMLEncode="TRUE"/></RenderPattern> <RenderPattern Name="PreviewNewPattern"><Property Select="DisplayName" HTMLEncode="TRUE"/></RenderPattern> </FieldType>

125. Custom Field Types ImplementationCustom Field Type PropertiesCustom field properties are defined in a PropertySchema/Fields element

126. Each custom property is defined as a Field element

127. Custom field properties are available in code via the SPField. GetCustomPropertymethodNote: The SPField.Updatemethod is not called when a new instance of a custom field type is added to a list. Only the SPField.OnAddedmethod gets called.Two ways to render the custom properties:

128. Using the PropertySchemaelementNote: There seems to be a bug in the PropertySchema element rendering system. The edit form for the list field does not bind the custom field property values to the form control correctly. Instead of binding the to the property values, the form binds to the property display names. The only known workaround is to use the next option.Using a field editor user control<FieldType> <Field Name="TypeName">USAddress</Field> … <PropertySchema> <Fields> <Field Name="DefaultState" DisplayName="Default State" MaxLength="2" DisplaySize="2" Type="Text"> <Default>WA</Default> </Field> <Field Name="DefaultZip" DisplayName="Default Zip" MaxLength="5" DisplaySize="5" Type="Text"> <Default>98052</Default> </Field> </Fields> </PropertySchema></FieldType>

129. Custom Field Types ImplementationCustom Field Data ValidationCustom field types are validated by overriding the SPField. GetValidatedStringmethod in the field class

130. Throw the SPField.SPFieldValidationExceptionexception when the supplied field value is not for the fieldCustom Field Types ImplementationCustom Field Value ClassesCustom field value classes do two primary tasks:

131. Convert field value as represented by managed types into a string

132. Done by overriding the SPField. GetValidatedStringmethod in the custom field class

133. The default implementation calls the ValueClass.ToStringmethod to get the string

134. Convert a string field valueback to a managed type

135. Done by overriding theSPField. GetFieldValuemethod in the custom field class

136. Value classes must be serializable, implementing the ToStringmethodCustom Field Types ImplementationCustom Field Type DeploymentFldtypes*.xml file must get copied to the "%CommonProgramFiles%\Microsoft Shared\web server extensions\12\TEMPLATE\XML\“ directory

137. Assemblies that implement the custom field, custom field values, rendering controls must be deployed to the GAC

138. Any assemblies referenced by the custom field assemblies must also reside in the GAC

139. Requires an IIS application pool recycle or an IISRESET in order for changes to take affect.

140. The fldtype*.xml files are reparsed by the IIS worker process

141. The assemblies loaded from the GAC are un-cached and re-cached by the IIS worker processDemoDemoCode walkthrough and demo of Media Field Typehttp://wsswmpcft.codeplex.com

142. CloseoutSummaryDefining custom field types

143. Reviewing the business cases that justify creation of custom field types

144. Comparison between custom field types and other WSS extensibility

145. Code walkthrough and demo of several custom field type implementationsCloseoutAdditional ResourcesBlack Blade Associateshttp://www.blackbladeinc.com“Things that should be Easy” by Eugene Rosenfeldhttp://thingsthatshouldbeeasy.blogspot.com/Phone number custom field type by Morgan Everett & Mark Collinshttp://www.sharethispoint.com/archive/2006/08/07/23.aspx#codetwoSharePoint SDK sample: How to create a custom field controlhttp://msdn2.microsoft.com/en-us/library/aa981226.aspxSharePoint Server 2007 Visual How Toshttp://msdn2.microsoft.com/en-us/library/bb530308.aspx

146. CloseoutQuestions?

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